Commencement is an another word for graduation which refers to a ceremony someone would be bound to attend after he or she finishes their entire school work(or after they did a certain required amount of work as to do so) before going out into the society(or move ahead in order to recieve more advanced education)

"Man....never thought I can get this far...
I mean, it's hard to believe....
that my school life is...finally OVER."